> Over an 8-hour work shift, an average, healthy, well-fed and motivated manual laborer may sustain an output of around 75 watts of work.

That's before conversion & transmission losses (especially as the converter will need to handle wildly varying inputs)

And even if we ignore these, according to 10.1109/MSPEC.2011.5910449:

> Let’s assume that the average piece of exercise equipment is in use 5 hours a day, 365 days a year. If each patron generates 100 watts while using it, that machine creates some 183 kilowatt-hours of electricity a year. Commercial power costs about 10 cents per kilowatt-hour on average in the United States, so the electricity produced in a year from one machine is worth about US $18 dollars.

Same for these solar panels on a car, too. Solar panels aren't the nicest things to manufacture right now. Putting them on a platform this poor is silly when you could put them somewhere more effective. If they were dirt cheap and harmless to create, opportunity costs might be less of an issue, but even today, they aren't dirt cheap and the aren't harmless to manufacture. They should be used effectively, not for show or feelings.